Preheat the oven to 375°F and line a baking sheet with parchment paper.
In a mixing bowl, combine the ground beef, breadcrumbs, egg, minced garlic, oregano, basil, parsley, 1/4 cup Parmesan, 1/2 tsp salt, and black pepper. Mix until evenly blended.
Divide the mixture into four equal portions and shape each into a small loaf. Place them on the prepared baking sheet.
Spoon 2 tablespoons of marinara sauce over each meatloaf. Bake for 25 minutes until the internal temperature reaches 160°F.
While the meatloaves bake, bring 4 cups of water and 1/2 tsp salt to a boil in a medium saucepan. Slowly whisk in the cornmeal.
Reduce heat to low and cook the polenta, stirring often, for 15 minutes until thick and creamy. Stir in the butter and 1/2 cup Parmesan until melted and smooth.
Spoon the polenta onto plates and top each serving with one mini meatloaf.